如何在 JavaFX 中为 ComboBox 中的项目添加值
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How do I add a value to items in a ComboBox in JavaFX
提问by user6587841
How can I add a value to items in a combo box so when the user selects an item from the ComboBoxI am able to display the price for that item
如何为组合框中的项目添加值，以便当用户从 中选择项目时，ComboBox我能够显示该项目的价格
Eg. if the user selects an animal I can display the price of that animal. The
the user selects dogthen I can display the price of $45.
例如。如果用户选择一种动物，我可以显示该动物的价格。用户选择dog然后我可以显示价格$45。
public class comboBox extends Application {
Stage window;
Scene scene;
Button button;
ComboBox<String> comboBox;
public static void main(String[] args) {
launch(args);
}
@Override
public void start(Stage primaryStage) throws Exception {
window = primaryStage;
window.setTitle("ComboBox");
button = new Button("Submit");
comboBox = new ComboBox<>();
comboBox.getItems().addAll(
"cat",
"dog",
"bird"
);
comboBox.setPromptText("Please select one");
button.setOnAction(e -> printPrice());
VBox layout = new VBox(10);
layout.setPadding(new Insets(60, 60, 60, 60));
layout.getChildren().addAll(comboBox, button);
scene = new Scene(layout, 450, 350);
window.setScene(scene);
window.show();
}
private void printPrice(){
System.out.println(comboBox.getValue());
}
}
I have tried to fix the code and this is what I got there is still a few errors anyone know what I am doing wrong?
我试图修复代码，这就是我得到的还有一些错误有人知道我做错了什么吗？
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ComboBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
import javafx.collections.FXCollections;
public class animals extends Application {
Stage window;
Scene scene;
Button button;
ComboBox<String> comboBox;
public static void main(String[] args) {
launch(args);
}
@Override
public void start(Stage primaryStage) throws Exception {
window = primaryStage;
window.setTitle("ComboBox ");
button = new Button("Submit");
comboBox.setConverter(new StringConverter<Animal>() {
@Override
public String toString(Animal object) {
return object.getName();
}
@Override
public Animal fromString(String string) {
return null;
}
});
ComboBox<Animal> comboBox = new ComboBox<Animal>();
comboBox.setItems(FXCollections.observableArrayList(new Animal("Dog", 30.12), new Animal("Cat", 23.23), new Animal("Bird", 15.0)));
comboBox.valueProperty().addListener((obs, oldVal, newVal) -> System.out.println("Price of the " + newVal.getName() + " is : " + newVal.getPrice())); }
VBox layout = new VBox(10);
layout.setPadding(new Insets(60, 60, 60, 60));
layout.getChildren().addAll(comboBox, button);
scene = new Scene(layout, 500, 350);
window.setScene(scene);
window.show();
}
public class Animal {
private String name;
private Double price;
public Double getPrice() {
return price;
}
public String getName() {
return name;
}
public Animal(String name, Double price) {
this.name = name;
this.price = price;
}
}
also, how would I be able to display the price under the combo box after the user selects an animal? so it would say 'the price for that animal cost'
另外，在用户选择动物后，我如何能够在组合框下显示价格？所以它会说“动物成本的价格”
回答by DVarga
You should provide a data model to the ComboBoxwhich stores the name and the price of the animal, for example instances of the class Animal.
您应该提供一个数据模型来ComboBox存储动物的名称和价格，例如类的实例Animal。
public class Animal {
private String name;
private Double price;
public Double getPrice() {
return price;
}
public String getName() {
return name;
}
public Animal(String name, Double price) {
this.name = name;
this.price = price;
}
}
Then in your ComboBoxyou can display these Animalinstances:
然后在您ComboBox可以显示这些Animal实例：
ComboBox<Animal> comboBox = new ComboBox<Animal>();
comboBox.setItems(FXCollections.observableArrayList(
new Animal("Dog", 30.12),
new Animal("Cat", 23.23),
new Animal("Bird", 15.0)));
comboBox.valueProperty().addListener((obs, oldVal, newVal) ->
System.out.println("Price of the " + newVal.getName() + " is : " + newVal.getPrice()));
The only thing left to display the name of the animals on the ComboBoxrather than the objects itself. To achieve this, you can use for example a StringConverter:
唯一剩下的就是ComboBox在物体上而不是物体本身上显示动物的名字。为此，您可以使用例如 a StringConverter：
comboBox.setConverter(new StringConverter<Animal>() {
@Override
public String toString(Animal object) {
return object.getName();
}
@Override
public Animal fromString(String string) {
return null;
}
});
On value change, the output is like:
在值更改时，输出如下：
Price of the Cat is : 23.23
Price of the Dog is : 30.12
Price of the Bird is : 15.0
An MCVE:
一个 MCVE：
public class Animals extends Application {
private ComboBox<Animal> comboBox = new ComboBox<>();
private Text textNamePrice = new Text();
public static void main(String[] args) { launch(args); }
@Override
public void start(Stage primaryStage) throws Exception {
comboBox.setConverter(new StringConverter<Animal>() {
@Override
public String toString(Animal object) {
return object.getName();
}
@Override
public Animal fromString(String string) {
return null;
}
});
comboBox.setItems(FXCollections.observableArrayList(new Animal("Dog", 30.12),
new Animal("Cat", 23.23),
new Animal("Bird", 15.0)));
comboBox.valueProperty().addListener((obs, oldVal, newVal) -> {
String selectionText = "Price of the " + newVal.getName() + " is : " + newVal.getPrice();
System.out.println(selectionText);
textNamePrice.setText(selectionText);
});
VBox layout = new VBox(10);
layout.setPadding(new Insets(60, 60, 60, 60));
layout.getChildren().addAll(comboBox, textNamePrice);
Scene scene = new Scene(layout, 500, 350);
primaryStage.setScene(scene);
primaryStage.show();
}
public class Animal {
private String name;
private Double price;
public Double getPrice() { return price; }
public String getName() { return name; }
public Animal(String name, Double price) {
this.name = name;
this.price = price;
}
}
}
